1. Field of the Invention
The present invention relates to an apparatus for cleaning the atmosphere; and more particularly to a vehicle comprising at least one atmosphere contacting surface having a pollution treating composition thereon, and a related method and composition.
2. Discussion of the Related Art
A review of literature relating to pollution control reveals that the general approach is to reactively clean waste streams entering the environment. If too much of one pollutant or another is detected or being discharged, the tendency has been to focus on the source of the pollutant, the cause of the pollutant or the waste stream containing the pollutant. For the most part gaseous streams are treated to reduce the pollutants prior to entering the atmosphere.
It has been disclosed to treat atmospheric air directed into a confined space to remove undesirable components in the air. However, there has been little effort to treat pollutants which are already in the environment; the environment has been left to its own self cleansing systems. References are known which disclose proactively cleaning the environment. U.S. Pat. No. 3,738,088 discloses an air filtering assembly for cleaning pollution from the ambient air by utilizing a vehicle as a mobile cleaning device. A variety of elements are disclosed to be used in combination with a vehicle to clean the ambient air as the vehicle is driven through the environment. In particular, there is disclosed ducting to control air stream velocity and direct the air to various filter means. The filter means can include filters and electronic precipitators. Catalyzed postfilters are disclosed to be useful to treat nonparticulate or aerosol pollution such as carbon monoxide, unburned hydrocarbons, nitrous oxide and/or sulfur oxides, and the like. German Patent DE 43 18 738 C1 also discloses a process for the physical and chemical cleaning of outside air. Motor vehicles are used as carriers of conventional filters and/or catalysts, which do not constitute operational components of the vehicle but are used to directly clean atmospheric air.
Another approach is disclosed in U.S. Pat. No. 5,147,429. There is disclosed a mobile airborne air cleaning station. In particular this patent features a dirigible for collecting air. The dirigible has a plurality of different types of air cleaning devices contained therein. The air cleaning devices disclosed include wet scrubbers, filtration machines, and cyclonic spray scrubbers.
The difficulty with the above recited devices disclosed to proactively clean the atmospheric air is that they require new and additional equipment. Even the modified vehicle disclosed in U.S. Pat. No. 3,738,088 requires ducting and filters which can include catalytic filters.
DE 40 07 965 C2 to Klaus Hager discloses a catalyst comprising copper oxides for converting ozone and a mixture of copper oxides and manganese oxides for converting carbon monoxide. The catalyst can be applied as a coating to a self heating radiator, oil coolers or charged-air coolers. The catalyst coating comprises heat resistant binders which are also gas permeable. It is indicated that the copper oxides and manganese oxides are widely used in gas mask filters and have the disadvantage of being poisoned by water vapor. However, the heating of the surfaces of the automobile during operation evaporates the water. In this way, continuous use of the catalyst is possible since no drying agent is necessary.
Manganese oxides are known to catalyze the oxidation of ozone to form oxygen. Many commercially available types of manganese compound and compositions, including alpha manganese oxide are disclosed to catalyze the reaction of ozone to form oxygen. In particular, it is known to use the cryptomelane form of alpha manganese oxide to catalyze the reaction of ozone to form oxygen.
Alpha manganese oxides are disclosed in references such as O""Young, Hydrothermal Synthesis of Manganese Oxides with Tunnel Structures, Modern Analytical Techniques for Analysis of Petroleum, presented at the Symposium on Advances in Zeolites and Pillared Clay Structures before the Division of Petroleum Chemistry, Inc. American Chemical Society New York City Meeting, Aug. 25-30, 1991 beginning at page 348. Such materials are also disclosed in U.S. Pat. No. 5,340,562 to O""Young, et al. Additionally, forms of xcex1-MnO2 are disclosed in McKenzie, the Synthesis of Birnessite, Cryptomelane, and Some Other Oxides and Hydroxides of Manganese, Mineralogical Magazine, December 1971, Vol. 38, pp. 493-502. For the purposes of the present invention, xcex1-MnO2 is defined to include hollandite (BaMn8O16.xH2O), cryptomelane (KMn8O16.xH2O), manjiroite (NaMn8O16.xH2O) and coronadite (PbMn8O16.xH2O). O""Young discloses these materials to have a three dimensional framework tunnel structure (U.S. Pat. No. 5,340,562 and O""Young Hydrothermal Synthesis of Manganese Oxides with Tunnel Structures both hereby incorporated by reference). For the purposes of the present invention, xcex1-MnO2 is considered to have a 2xc3x972 tunnel structure and to include hollandite, cryptomelane, manjiroite and coronadite.
The present invention relates to an apparatus, method and composition to treat the atmosphere. For the purposes of the present invention atmosphere is defined as the mass of air surrounding the earth.
The present invention is directed to an apparatus and related method for treating the atmosphere comprising a vehicle and a means such as a motor to translate the vehicle from one place to another through the atmosphere. The vehicle comprises at least one atmosphere contacting vehicle surface and a pollutant treating composition located on that surface. The atmosphere contacting surface is a surface of a component of the vehicle that is in direct contact with the atmosphere. Preferred and useful atmosphere contacting surfaces include body surfaces, wind deflector surfaces, grill surfaces, mirror backs and the surfaces of xe2x80x9cunder the hoodxe2x80x9d components. Preferred atmosphere contacting surfaces are located within the body of the motor vehicle, typically in proximity to the engine, i.e., the engine compartment. The surfaces are preferably the surfaces of cooling means which comprise an in flow path for liquids or gases through a coolant walled enclosure such as tubes or a housing and an outer surface on which is located fins to enhance heat transfer. Preferred atmosphere contacting surfaces comprise a finned outer surface and are selected from the outer surfaces of the radiator, air conditioner condenser, the surfaces of the radiator fan, engine oil cooler, transmission oil cooler, power steering fluid cooler and air charge cooler also referred to as an intercooler or after cooler. The most preferred atmosphere contacting surfaces are the outer surfaces of the air conditioner condenser and radiator due to their large surface area and relatively high ambient operating temperatures of from about 40xc2x0 C. to 135xc2x0 C. and typically up to 110xc2x0 C.
An advantage of the present invention is that the atmosphere contacting surface useful to support a pollution treating composition can be the surface of existing vehicle components. No additional filter, or apparatus to support a pollutant treating composition, is required. Accordingly, the apparatus and method of the present invention can be located on existing components of new cars or retrofitted onto old cars. Retrofitting may comprise coating a suitable pollutant treating composition on an existing vehicle surface which comes in contact with atmospheric air as the vehicle is driven through the atmosphere.
The present invention is directed to compositions, methods and articles to treat pollutants in air. Such pollutants may typically comprise from 0 to 400 parts, more typically 1 to 300, and yet more typically 1 to 200, parts per billion (ppb) ozone; 0 to 30 parts, and more typically 1 to 20, parts per million (ppm) carbon monoxide; and 2 to 3000 ppb unsaturated hydrocarbon compounds such as C2 to about C20 olefins and partially oxygenated hydrocarbons such as alcohols, aldehydes, esters, ethers, ketones and the like. Typical hydrocarbons which can be treated include, but are not limited to, propylene, butylene, formaldehyde and other airborne hydrocarbon gases and vapors. Other pollutants present may include nitrogen oxides and sulfur oxides. The National Ambient Air Quality Standard for ozone is 120 ppb, and for carbon monoxide is 9 ppm.
Pollutant treating compositions include catalyst compositions useful for catalyzing the conversion of pollutants present in the atmosphere to non-objectionable materials. Alternatively, adsorption compositions can be used as the pollutant treating composition to adsorb pollutants which can be destroyed upon adsorption, or stored for further treatment at a later time.
Catalyst compositions can be used which can assist in the conversion of the pollutants to harmless compounds or to less harmful compounds. Useful and preferred catalyst compositions include compositions which catalyze the reaction of ozone to form oxygen, catalyze the reaction of carbon monoxide to form carbon dioxide, and/or catalyze the reaction of hydrocarbons to form water and carbon dioxide. Specific and preferred catalysts to catalyze the reaction of hydrocarbons are useful for catalyzing the reaction of low molecular weight unsaturated hydrocarbons having from two to twenty carbons and at least one double bond, such as C2 to about C8 mono-olefins. Such low molecular weight hydrocarbons have been identified as being sufficiently reactive to cause smog. Particular olefins which can be reacted include propylene and butylene. A useful and preferred catalyst can catalyze the reactions of both ozone and carbon monoxide; and preferably ozone, carbon monoxide and hydrocarbons.
Ozonexe2x80x94Useful and preferred catalyst compositions to treat ozone include a composition comprising manganese compounds including oxides such as Mn2O3 and MnO2 with a preferred composition comprising xcex1-MnO2, and cryptomelane being most preferred. Other useful and preferred compositions include a mixture of MnO2 and CuO. Specific and preferred compositions comprise hopcalite which contains CuO and MnO2 and, more preferably CARULITE(copyright) catalyst which contains MnO2, CuO and Al2O3 and sold by the Carus Chemical Co. An alternative composition comprises a refractory metal oxide support on which is dispersed a catalytically effective amount of a palladium component and preferably also includes a manganese component. Also useful is a catalyst comprising a precious metal component, preferably a platinum component on a support of coprecipitated zirconia and manganese oxide. The use of this coprecipitated support has been found to be particularly effective to enable a platinum component to be used to treat ozone. Yet another composition which can result in the conversion of ozone to oxygen comprises carbon, and palladium or platinum supported on carbon, manganese dioxide, CARULITE(copyright) catalyst and/or hopcalite. Manganese supported on a refractory oxide such as alumina has also been found to be useful.
Carbon Monoxidexe2x80x94Useful and preferred catalyst compositions to treat carbon monoxide include a composition comprising a refractory metal oxide support on which is dispersed a catalytically effective amount of a platinum and/or palladium component, preferably a platinum component. A most preferred catalyst composition to treat carbon monoxide comprises a reduced platinum group component supported on a refractory metal oxide, preferably titania. Useful catalytic materials include precious metal components including platinum group components which include the metals and their compounds. Such metals can be selected from platinum, palladium, rhodium and ruthenium, gold and/or silver components. Platinum will also result in the catalytic reaction of ozone. Also useful is a catalyst comprising a precious metal component, preferably a platinum component on a support of coprecipitated zirconia and manganese dioxide. Preferably, this catalyst embodiment is reduced. Other useful compositions which can convert carbon monoxide to carbon dioxide include a platinum component supported on carbon or a support comprising manganese dioxide. Preferred catalysts to treat such pollutants are reduced. Another composition useful to treat carbon monoxide comprises a platinum group metal component, preferably a platinum component, a refractory oxide support, preferably alumina and titania and at least one metal component selected from a tungsten component and rhenium component, preferably in the metal oxide form.
Hydrocarbonsxe2x80x94Useful and preferred catalyst compositions to treat unsaturated hydrocarbons including C2 to about C20 olefins and typically C2 to C8 mono-olefins such as propylene and partially oxygenated hydrocarbons as recited have been found to be the same type as recited for use in catalyzing the reaction of carbon monoxide with the preferred compositions for unsaturated hydrocarbons comprising a reduced platinum and/or palladium component and a refractory metal oxide support for the platinum component. A preferred refractory metal oxide support is titania. Other useful compositions which can convert hydrocarbons to carbon dioxide and water include a platinum component supported on carbon or a support comprising manganese dioxide. Preferred catalysts to treat such pollutants are reduced. Another composition useful to convert hydrocarbons comprises a platinum group metal component, preferably a platinum component, a refractory oxide support, preferably alumina and titania and at least one metal component selected from a tungsten component and rhenium component, preferably in the metal oxide form. A combination of a platinum component and a palladium component results in improved CO conversion at an increase in cost and is most preferred where greater conversion is desired and cost increase is acceptable.
Ozone and Carbon Monoxidexe2x80x94A useful and preferred catalyst which can treat both ozone and carbon monoxide comprises a support such as a refractory metal oxide support on which is dispersed a precious metal component. The refractory oxide support can comprise a support component selected from the group consisting of ceria, alumina, silica, titania, zirconia, and mixtures thereof. Also useful as a support for precious metal catalyst components is a coprecipitate of zirconia and manganese oxides. Most preferably, this support is used with a platinum component and the catalyst is in reduced form. This single catalyst has been found to effectively treat both ozone and carbon monoxide. Other useful and preferred precious metal components are comprised of precious metal components selected from palladium and also platinum components with palladium preferred. A combination of a ceria support with a palladium component results in an effective catalyst for treating both ozone and carbon monoxide. Other useful and preferred catalysts to treat both ozone and carbon monoxide include a platinum group component, preferably a platinum component and/or palladium component and more preferably a platinum component, on titania or on a combination of zirconia and silica. A combination of a platinum component and a palladium component results in improved CO conversion at an increase in cost and is most preferred where greater conversion is desired and cost increase is acceptable. Other useful compositions which can convert ozone to oxygen and carbon monoxide to carbon dioxide include a platinum component supported on carbon or on a support comprising manganese dioxide. Preferred catalysts are reduced.
Ozone, Carbon Monoxide and Hydrocarbonsxe2x80x94A useful and preferred catalyst which can treat ozone, carbon monoxide and hydrocarbons, typically low molecular weight olefins (C2 to about C20) and typically C2 to C8 mono-olefins and partially oxygenated hydrocarbons as recited comprises a support, preferably a refractory metal oxide support on which is dispersed a precious metal component. The refractory metal oxide support can comprise a support component selected from the group consisting of ceria, alumina, titania, zirconia and mixtures thereof with titania most preferred. Useful and preferred precious metal components are comprised of precious metal components selected from platinum group components including palladium and/or platinum components with platinum most preferred. It has been found that a combination of a titania support with a platinum component results in the most effective catalyst for treating ozone, carbon monoxide and low molecular weight gaseous olefin compounds. A combination of a platinum component and a palladium component results in improved CO and hydrocarbon conversion at an increase in cost and is most preferred where greater conversion is desired and cost increase is acceptable. It is preferred to reduce the platinum group components with a suitable reducing agent. Other useful compositions which can convert ozone to oxygen, carbon monoxide to carbon dioxide, and hydrocarbons to carbon dioxide include a platinum component supported on carbon, a support comprising manganese dioxide, or a support comprising a coprecipitate of manganese oxides and zirconia. Preferred catalysts are reduced.
The above compositions can be applied by coating to at least one atmosphere contacting vehicle surface. Particularly preferred compositions catalyze the destruction of ozone, carbon monoxide and/or unsaturated low molecular weight olefinic compounds at ambient conditions or ambient operating conditions. Ambient conditions are the conditions of the atmosphere. By ambient operating conditions it is meant the conditions, such as temperature, of the atmosphere contacting surface during normal operation of the vehicle without the use of additional energy directed to heating the pollutant treating composition. Certain atmosphere contacting surfaces such as a grill or wind deflector can be at the same or similar temperature as the atmosphere. It has been found that preferred catalysts which catalyze the reaction of ozone can catalyze the reaction of ozone at ambient conditions in ranges as low as 50xc2x0 C. to 30xc2x0 C.
Atmosphere contacting surfaces may have higher temperatures than the ambient atmospheric temperatures due to the nature of the operation of the component underlying the surface. For example, preferred atmosphere contacting surfaces are the surfaces of the air conditioning condenser and the radiator due to their high surface area. Where vehicles use air charge coolers, these are preferred due to high surface area and operating temperatures of from ambient to 250xc2x0 F. Normally, during ambient operating conditions the surfaces of these components increase to higher temperature levels than the ambient environment due to the nature of their operation. After the vehicle motor has warmed up, these components are typically at temperatures which range up to about 130xc2x0 C. and typically from 40xc2x0 C. to 110xc2x0 C. The temperature range of these atmosphere contacting surfaces helps to enhance the conversion rates of the ozone, carbon monoxide and hydrocarbon catalysts supported on such surfaces. Air charge coolers operate at temperatures up to about 130xc2x0 C. and typically from 60xc2x0 C. to 130xc2x0 C.
Various of the catalyst compositions can be combined, and a combined coating applied to the atmosphere contacting surface. Alternatively, different surfaces or different parts of the same surface can be coated with different catalyst compositions.
The method and apparatus of the present invention are designed so that the pollutants can be treated at ambient atmospheric conditions or at the ambient operating conditions of the vehicle atmosphere contacting surface. The present invention is particularly useful for treating ozone by coating motor vehicle atmosphere contacting surfaces with suitable catalysts useful to destroy such pollutants even at ambient conditions, and at vehicle surface temperatures typically from at least 0xc2x0 C., preferably from 10xc2x0 C. to 105xc2x0 C., and more preferably from 40xc2x0 C. to 100xc2x0 C. Carbon monoxide is preferably treated at atmosphere contacting surface temperatures from 40xc2x0 C. to 105xc2x0 C. Low molecular weight hydrocarbons, typically unsaturated hydrocarbons having at least one unsaturated bond, such as C2 to about C20 olefins and typically C2 to C8 mono-olefins, are preferably treated at atmosphere contacting surface temperatures of from 40xc2x0 C. to 105xc2x0 C. The percent conversion of ozone, carbon monoxide and/or hydrocarbons depends on the temperature and space velocity of the atmospheric air relative to the atmosphere contacting surface, and the temperature of the atmosphere contacting surface.
Accordingly, the present invention, in most preferred embodiments can result in at least reducing the ozone, carbon monoxide and/or hydrocarbon levels present in the atmosphere without the addition of any mechanical features or energy source to existing vehicles, particularly motor vehicles. Additionally, the catalytic reaction takes place at the normal ambient operating conditions experienced by the surfaces of these motor vehicle elements so that no changes in the construction or method of operation of the motor vehicle are required.
While the apparatus and method of the present invention are generally directed to treating the atmosphere, it will be appreciated that variations of the apparatus are contemplated for use to treat volumes of air in enclosed spaces. For example, a motor vehicle having an atmosphere contacting surface supporting a pollutant treating composition can be used to treat the air within factories, mines and tunnels. Such apparatus can include vehicles used in such environments.
While the preferred embodiments of the present invention are directed to the destruction of pollutants at the ambient operating temperatures of the atmosphere contacting surface, it is also desirable to treat pollutants which have a catalyzed reaction temperature higher than the ambient temperature or ambient operating temperature of the atmosphere contacting surface. Such pollutants include hydrocarbons and nitrogen oxides and any carbon monoxide which bypasses or is not treated at the atmosphere contacting surface. These pollutants can be treated at higher temperatures typically in the range of at least 100xc2x0 C. to 450xc2x0 C. This can be accomplished, for example, by the use of an auxiliary heated catalyzed surface. By an auxiliary heated surface, it is meant that there are supplemental means to heat the surface. A preferred auxiliary heated surface is the surface of an electrically heated catalyzed monolith such as an electrically heated catalyzed metal honeycomb of the type known to those skilled in the art. Electricity can be provided by batteries or a generator such as are present in motor vehicles. The catalyst composition can be any well known oxidation and/or reduction catalyst, preferably a three way catalyst (TWC) comprising precious group metals such as platinum, palladium, rhodium and the like supported on refractory oxide supports. An auxiliary heated catalyzed surface can be used in combination with, and preferably downstream of, the vehicle atmosphere contacting surface to further treat the pollutants.
As previously stated, adsorption compositions can also be used to adsorb pollutants such as hydrocarbons and/or particulate matter for later oxidation or subsequent removal. Useful and preferred adsorption compositions include zeolites, other molecular sieves, carbon, and Group IIA alkaline earth metal oxides such as calcium oxide. Hydrocarbons and particulate matter can be adsorbed from 0xc2x0 C. to 110xc2x0 C. and subsequently treated by desorption followed by catalytic reaction or incineration.
It is preferred to coat areas of the vehicle that have a relatively high surface area exposed to a large flow rate of atmospheric air as the motor vehicle is driven through the environment. For land use motor vehicles, particularly preferred atmosphere contacting surfaces include the radiator, fan blades, the air conditioning condenser or heat exchanger, air charge cooler, engine oil cooler, transmission oil cooler, and wind deflectors of the type used on the roof of truck cabs.
Most preferably, the atmosphere contacting surface is a surface of a radiator. The radiator has a large surface area for enhanced cooling of internal combustion engine fluid coolants. By applying a catalyst to be supported on the radiator surface, advantage can be taken of the large honeycomb-like surface area, usually with little or no effect on the cooling function of the radiator. The high honeycomb-like surface area enables a maximization of contact of the catalyst with the air passing through the honeycomb-like design of the radiator. Additionally, radiators in many automobiles are located behind the air conditioner condenser and are thereby protected by the air conditioner condenser.
The present invention includes methods to coat pollutant treating compositions on to atmosphere contacting surfaces of motor vehicles. In particular, the present invention includes a method to coat catalyst compositions onto finned elements such as radiators, air conditioner condensers, and air charge coolers.
Calculations suggest that in motor vehicle traffic congested areas, there are a sufficient number of motor vehicles to significantly impact pollutants treated in accordance with the present invention. For example, in Southern California""s South Coast Air Quality Management District, there are approximately eight million cars. It has been calculated that if each car travels 20 miles per day, all of the air in this region to an altitude of 100 feet can be cycled through radiators in one week.